This document has been developed by the Centers for Disease
Control (CDC) to update recommendations for prevention of
transmission of human immunodeficiency virus (HIV) and hepatitis
B virus (HBV) in the health-care setting. Current data suggest
that the risk for such transmission from a health-care worker
(HCW) to a patient during an invasive procedure is small; a
precise assessment of the risk is not yet available. This
document contains recommendations to provide guidance for
prevention of HIV and HBV transmission during those invasive
procedures that are considered exposure-prone.
INTRODUCTION

Recommendations have been made by the Centers for Disease
Control (CDC) for the prevention of transmission of the human
immunodeficiency virus (HIV) and the hepatitis B virus (HBV) in
health-care settings (1-6). These recommendations emphasize
adherence to universal precautions that require that blood and
other specified body fluids of all patients be handled as if they
contain blood-borne pathogens (1,2).

Previous guidelines contained precautions to be used during
invasive procedures (defined in Appendix) and recommendations for
the management of HIV- and HBV-infected health-care workers
(HCWs) (1). These guidelines did not include specific
recommendations on testing HCWs for HIV or HBV infection, and
they did not provide guidance on which invasive procedures may
represent increased risk to the patient.

The recommendations outlined in this document are based on
the following considerations:

Infected HCWs who adhere to universal precautions and who

do not perform invasive procedures pose no risk for transmitting
HIV or HBV to patients.

HIV is transmitted much less readily than HBV.
In the interim, until further data are available, additional

precautions are prudent to prevent HIV and HBV transmission
during procedures that have been linked to HCW-to-patient HBV
transmission or that are considered exposure-prone.
BACKGROUND
Infection-Control Practices

Previous recommendations have specified that
infection-control programs should incorporate principles of
universal precautions (i.e., appropriate use of hand washing,
protective barriers, and care in the use and disposal of needles
and other sharp instruments) and should maintain these
precautions rigorously in all health-care settings (1,2,5).
Proper application of these principles will assist in minimizing
the risk of transmission of HIV or HBV from patient to HCW, HCW
to patient, or patient to patient.

As part of standard infection-control practice, instruments
and other reusable equipment used in performing invasive
procedures should be appropriately disinfected and sterilized as
follows (7):

Equipment and devices that enter the patient's vascular

system or other normally sterile areas of the body should be
sterilized before being used for each patient.

Equipment and devices that touch intact mucous membranes

but do not penetrate the patient's body surfaces should be
sterilized when possible or undergo high-level disinfection if
they cannot be sterilized before being used for each patient.

Equipment and devices that do not touch the patient or

that only touch intact skin of the patient need only be cleaned
with a detergent or as indicated by the manufacturer.

Compliance with universal precautions and recommendations
for disinfection and sterilization of medical devices should be
scrupulously monitored in all health-care settings (1, 7, 8).
Training of HCWs in proper infection-control technique should
begin in professional and vocational schools and continue as an
ongoing process. Institutions should provide all HCWs with
appropriate inservice education regarding infection control and
safety and should establish procedures for monitoring compliance
with infection-control policies.

All HCWs who might be exposed to blood in an occupational
setting should receive hepatitis B vaccine, preferably during
their period of professional training and before any occupational
exposures could occur (8, 9).

Transmission of HBV During Invasive Procedures

Since the introduction of serologic testing for HBV
infection in the early 1970s, there have been published reports
of 20 clusters in which a total of over 300 patients were
infected with HBV in association with treatment by an
HBV-infected HCW. In 12 of these clusters, the implicated HCW did
not routinely wear gloves; several HCWs also had skin lesions
that may have facilitated HBV transmission (10-22). These 12
clusters included nine linked to dentists or oral surgeons and
one cluster each linked to a general practitioner, an inhalation
therapist, and a cardiopulmonary-bypass-pump technician. The
clusters associated with the inhalation therapist and the
cardiopulmonary-bypass-pump technician--and some of the other 10
clusters--could possibly have been prevented if current
recommendations on universal precautions, including glove use,
had been in effect. In the remaining eight clusters, transmission
occurred despite glove use by the HCWs; five clusters were linked
to obstetricians or gynecologists, and three were linked to
cardiovascular surgeons (6, 22-28). In addition, recent
unpublished reports strongly suggest HBV transmission from three
surgeons to patients in 1989 and 1990 during colorectal (CDC,
unpublished data), abdominal, and cardiothoracic surgery (29).

Seven of the HCWs who were linked to published clusters in
the United States were allowed to perform invasive procedures
following modification of invasive techniques (e.g., double
gloving and restriction of certain high-risk procedures) (6,11-
13,15,16, 24). For five HCWs, no further transmission to patients
was observed. In two instances involving an
obstetrician/gynecologist and an oral surgeon, HBV was
transmitted to patients after techniques were modified (6, 12).

Review of the 20 published studies indicates that a
combination of risk factors accounted for transmission of HBV
from HCWs to patients. Of the HCWs whose hepatitis B e antigen
(HBeAg) status was determined (17 of 20), all were HBeAg
positive. The presence of HBeAg in serum is associated with
higher levels of circulating virus and therefore with greater
infectivity of hepatitis-B-surface-antigen (HBsAg)-positive
individuals; the risk of HBV transmission to an HCW after a
percutaneous exposure to HBeAg-positive blood is approximately
30% (30-32). In addition, each report indicated that the
potential existed for contamination of surgical wounds or
traumatized tissue, either from a major break in standard
infection-control practices (e.g., not wearing gloves during
invasive procedures) or from unintentional injury to the infected
HCW during invasive procedures (e.g., needle sticks incurred
while manipulating needles without being able to see them during
suturing).

Most reported clusters in the United States occurred before
awareness increased of the risks of transmission of blood-borne
pathogens in health-care settings and before emphasis was placed
on the use of universal precautions and hepatitis B vaccine among
HCWs. The limited number of reports of HBV transmission from HCWs
to patients in recent years may reflect the adoption of universal
precautions and increased use of HBV vaccine. However, the
limited number of recent reports does not preclude the occurrence
of undetected or unreported small clusters or individual
instances of transmission; routine use of gloves does not prevent
most injuries caused by sharp instruments and does not eliminate
the potential for exposure of a patient to an HCW's blood and
transmission of HBV (6, 22-29).

Transmission of HIV During Invasive Procedures

The risk of HIV transmission to an HCW after percutaneous
exposure to HIV-infected blood is considerably lower than the
risk of HBV transmission after percutaneous exposure to
HBeAg-positive blood (0.3% versus approximately 30%) (33-35).
Thus, the risk of transmission of HIV from an infected HCW to a
patient during an invasive procedure is likely to be
proportionately lower than the risk of HBV transmission from an
HBeAg-positive HCW to a patient during the same procedure. As
with HBV, the relative infectivity of HIV probably varies among
individuals and over time for a single individual. Unlike HBV
infection, however, there is currently no readily available
laboratory test for increased HIV infectivity.

Investigation of a cluster of HIV infections among patients
in the practice of one dentist with acquired immunodeficiency
syndrome (AIDS) strongly suggested that HIV was transmitted to
five of the approximately 850 patients evaluated through June
1991 (36-38). The investigation indicates that HIV transmission
occurred during dental care, although the precise mechanisms of
transmission have not been determined. In two other studies, when
patients cared for by a general surgeon and a surgical resident
who had AIDS were tested, all patients tested, 75 and 62,
respectively, were negative for HIV infection (39, 40). In a
fourth study, 143 patients who had been treated by a dental
student with HIV infection and were later tested were all
negative for HIV infection (41). In another investigation, HIV
antibody testing was offered to all patients whose surgical
procedures had been performed by a general surgeon within 7 years
before the surgeon's diagnosis of AIDS; the date at which the
surgeon became infected with HIV is unknown (42). Of 1,340
surgical patients contacted, 616 (46%) were tested for HIV. One
patient, a known intravenous drug user, was HIV positive when
tested but may already have been infected at the time of surgery.
HIV test results for the 615 other surgical patients were
negative (95% confidence interval for risk of transmission per
operation=0.0%-0.5%).

The limited number of participants and the differences in
procedures associated with these five investigations limit the
ability to generalize from them and to define precisely the risk
of HIV transmission from HIV-infected HCWs to patients. A precise
estimate of the risk of HIV transmission from infected HCWs to
patients can be determined only after careful evaluation of a
substantially larger number of patients whose exposure-prone
procedures have been performed by HIV-infected HCWs.

Exposure-Prone Procedures

Despite adherence to the principles of universal
precautions, certain invasive surgical and dental procedures have
been implicated in the transmission of HBV from infected HCWs to
patients, and should be considered exposure-prone. Reported
examples include certain oral, cardiothoracic, colorectal (CDC,
unpublished data), and obstetric/gynecologic procedures (6, 12,
22-29).

Certain other invasive procedures should also be considered
exposure-prone. In a prospective study CDC conducted in four
hospitals, one or more percutaneous injuries occurred among
surgical personnel during 96 (6.9%) of 1,382 operative procedures
on the general surgery, gynecology, orthopedic, cardiac, and
trauma services (43). Percutaneous exposure of the patient to the
HCW's blood may have occurred when the sharp object causing the
injury recontacted the patient's open wound in 28 (32%) of the 88
observed injuries to surgeons (range among surgical
specialties=8%-57%; range among hospitals=24%-42%).
Characteristics of exposure-prone procedures include digital
palpation of a needle tip in a body cavity or the simultaneous
presence of the HCW's fingers and a needle or other sharp
instrument or object in a poorly visualized or highly confined
anatomic site. Performance of exposure-prone procedures presents
a recognized risk of percutaneous injury to the HCW, and--if such
an injury occurs--the HCW's blood is likely to contact the
patient's body cavity, subcutaneous tissues, and/or mucous
membranes.

Experience with HBV indicates that invasive procedures that
do not have the above characteristics would be expected to pose
substantially lower risk, if any, of transmission of HIV and
other blood-borne pathogens from an infected HCW to patients.
RECOMMENDATIONS

Investigations of HIV and HBV transmission from HCWs to
patients indicate that, when HCWs adhere to recommended
infection-control procedures, the risk of transmitting HBV from
an infected HCW to a patient is small, and the risk of
transmitting HIV is likely to be even smaller. However, the
likelihood of exposure of the patient to an HCW's blood is
greater for certain procedures designated as exposure-prone. To
minimize the risk of HIV or HBV transmission, the following
measures are recommended:

--All HCWs should adhere to universal precautions, including
the appropriate use of hand washing, protective barriers, and
care in the use and disposal of needles and other sharp
instruments. HCWs who have exudative lesions or weeping
dermatitis should refrain from all direct patient care and from
handling patient-care equipment and devices used in performing
invasive procedures until the condition resolves. HCWs should
also comply with current guidelines for disinfection and
sterilization of reusable devices used in invasive procedures.

--Currently available data provide no basis for
recommendations to restrict the practice of HCWs infected with
HIV or HBV who perform invasive procedures not identified as
exposure-prone, provided the infected HCWs practice recommended
surgical or dental technique and comply with universal
precautions and current recommendations for
sterilization/disinfection.

--Exposure-prone procedures should be identified by
medical/surgical/dental organizations and institutions at which
the procedures are performed.

--HCWs who perform exposure-prone procedures should know
their HIV antibody status. HCWs who perform exposure-prone
procedures and who do not have serologic evidence of immunity to
HBV from vaccination or from previous infection should know their
HBsAg status and, if that is positive, should also know their
HBeAg status.

--HCWs who are infected with HIV or HBV (and are HBeAg
positive) should not perform exposure-prone procedures unless
they have sought counsel from an expert review panel and been
advised under what circumstances, if any, they may continue to
perform these procedures.* Such circumstances would include
notifying prospective patients of the HCW's seropositivity before
they undergo exposure-prone invasive procedures.

--Mandatory testing of HCWs for HIV antibody, HBsAg, or
HBeAg is not recommended. The current assessment of the risk that
infected HCWs will transmit HIV or HBV to patients during
exposure-prone procedures does not support the diversion of
resources that would be required to implement mandatory testing
programs. Compliance by HCWs with recommendations can be
increased through education, training, and appropriate
confidentiality safeguards.

*The review panel should include experts who represent a balanced
perspective. Such experts might include all of the following: a)
the HCW's personal physician(s), b) an infectious disease
specialist with expertise in the epidemiology of HIV and HBV
transmission, c) a health professional with expertise in the
procedures performed by the HCW, and d) state or local public
health official(s). If the HCW's practice is institutionally
based, the expert review panel might also include a member of the
infection-control committee, preferably a hospital
epidemiologist. HCWs who perform exposure-prone procedures
outside the hospital/institutional setting should seek advice
from appropriate state and local public health officials
regarding the review process. Panels must recognize the
importance of confidentiality and the privacy rights of infected
HCWs.
HCWS WHOSE PRACTICES ARE MODIFIED BECAUSE OF HIV OR HBV STATUS

HCWs whose practices are modified because of their HIV or
HBV infection status should, whenever possible, be provided
opportunities to continue appropriate patient-care activities.
Career counseling and job retraining should be encouraged to
promote the continued use of the HCW's talents, knowledge, and
skills. HCWs whose practices are modified because of HBV
infection should be reevaluated periodically to determine whether
their HBeAg status changes due to resolution of infection or as a
result of treatment (44).
NOTIFICATION OF PATIENTS AND FOLLOW-UP STUDIES

The public health benefit of notification of patients who
have had exposure-prone procedures performed by HCWs infected
with HIV or positive for HBeAg should be considered on a
case-by-case basis, taking into consideration an assessment of
specific risks, confidentiality issues, and available resources.
Carefully designed and implemented follow-up studies are
necessary to determine more precisely the risk of transmission
during such procedures. Decisions regarding notification and
follow-up studies should be made in consultation with state and
local public health officials.
ADDITIONAL NEEDS

Clearer definition of the nature, frequency, and circumstances
of blood contact between patients and HCWs during invasive
procedures.

Development and evaluation of new devices, protective
barriers, and techniques that may prevent such blood contact
without adversely affecting the quality of patient care.

More information on the potential for HIV and HBV transmission
through contaminated instruments.

Improvements in sterilization and disinfection techniques for
certain reusable equipment and devices.

Identification of factors that may influence the likelihood of
HIV or HBV transmission after exposure to HIV- or HBV-infected
blood.

An invasive procedure is defined as ``surgical entry into
tissues, cavities, or organs or repair of major traumatic
injuries'' associated with any of the following: ``1) an
operating or delivery room, emergency department, or outpatient
setting, including both physicians' and dentists' offices; 2)
cardiac catheterization and angiographic procedures; 3) a vaginal
or cesarean delivery or other invasive obstetric procedure during
which bleeding may occur; or 4) the manipulation, cutting, or
removal of any oral or perioral tissues, including tooth
structure, during which bleeding occurs or the potential for
bleeding exists.''
Reprinted from: Centers for Disease Control. Recommendation for
prevention of HIV transmission in health-care settings. MMWR
1987;36 (suppl. no. 2S):6S-7S.

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